Magenta metal complex azo compounds and inks and their use in ink-jet printing

ABSTRACT

A metal chelate compound obtainable from contacting a transition metal salt with a compound of the Formula (1):  
                 
wherein: x represents plural atoms required to form at least one optionally substituted 5- to 7-membered heterocyclic ring; and Ar is an optionally substituted stilbene, acenaphthylene, phenanthrene or anthracene group carrying a hydroxy, amino or carboxy group adjacent to the —N═N— group shown in Formula (1) or 6-hydroxyquinoline where the hydroxy group is adjacent to the —N═N— group shown in Formula (1); 
 
provided that when the compound of Formula (1) is of Formula:  
                 
that, p, the level of sulfonation, is not in the range 1 to 2. Also compositions, inks, printed substrates and inkjet cartridges.

This invention relates to compounds, to inks and to their use in ink-jetprinting (“IJP”). IJP is a non-impact printing technique in whichdroplets of ink are ejected through a fine nozzle onto a substratewithout bringing the nozzle into contact with the substrate.

There are many demanding performance requirements for compounds and inksused in IJP. For example they desirably provide sharp, non-featheredimages having good water-fastness, light-fastness and optical density.The inks are often required to dry quickly when applied to a substrateto prevent smudging, but they should not form a crust over the tip of anink-jet nozzle because this will stop the printer from working. The inksshould also be stable to storage over time without decomposing orforming a precipitate which could block the fine nozzle.

WO 01/48090 relates to metal chelate azo compounds which comprise anaphthol component and heterocyclic groups.

There is a need for compounds which meet the demanding performancerequirements in IJP and, in particular, having a good combination ofhigh chroma (i.e. brightness), high light-fastness and fastness tooxidising gases (e.g. ozone).

According to a first aspect of the present invention there is provided ametal chelate compound obtainable from contacting a transition metalsalt with a compound of the Formula (1) or a salt thereof:

wherein:

-   -   X represents plural atoms required to form at least one        optionally substituted 5- to 7-membered heterocyclic ring; and    -   Ar is an optionally substituted stilbene, acenaphthylene,        phenanthrene or anthracene group carrying a hydroxy, amino or        carboxy group adjacent to the —N═N— group shown in Formula (1)        or 6-hydroxyquinoline where the hydroxy group is adjacent to the        —N═N— group shown in Formula (1);    -   provided that when the compound of Formula (1) is of Formula:        that, p, the level of sulfonation, is not in the range 1 to 2.

The optionally substituted stilbene group is preferably of the Formula(2a) or Formula (2b):

wherein

-   -   Q is a hydroxy, amino or carboxy group positioned adjacent to        the —N═N— group shown in Formula (1);    -   G is a water-solubilising group; and    -   m and n are each independently 0, 1 or 2.

Preferably Q is a hydroxy group.

Preferably the value of (m+n) is greater than 1, more preferably 1 to 4and especially 1 to 2.

The values of m and n may represent either an integer, from when thecompound in made from a starting material already bearing thewater-solubilising group, or an average, from when thewater-solubilising group is introduced after synthesis of the compoundof Formula (2a) or (2b) e.g. via sulfonation.

Preferably each G independently is selected from sulfo, phosphate andcarboxy, more preferably all groups represented by G are sulfo.

The optionally substituted 6-hydroxyquinoline group is preferably ofFormula (3):

wherein:

-   -   the hydroxy group is positioned adjacent to the —N═N— group        shown in Formula (1);    -   G is a water-solubilising group; and    -   m is 0 to 4, preferably 0 to 2.

The value of m may represent either an integer, from when the compoundin made from a starting material already bearing the water-solubilisinggroup, or it may represent an average, from when the water-solubilisinggroup is introduced after synthesis of the compound of Formula (3) e.g.via sulfonation.

Preferably each G independently is selected from sulfo, phosphate andcarboxy, more preferably all groups represented by G are sulfo.

The optionally substituted phenanthrene group is preferably of Formula(4) and more preferably of Formula (4a):

wherein

-   -   M is C or N;    -   Q is a hydroxy, amino or carboxy group positioned adjacent to        the —N═N— group shown in Formula (1);    -   G is a water-solubilising group; and    -   m is greater than than 0, preferably 1 to 4 and more preferably        2 to 3.        wherein    -   Q is a hydroxy, amino or carboxy group positioned adjacent to        the —N═N— group shown in Formula (1);    -   G is a water-solubilising group; and    -   m is greater than 0, preferably 1 to 4 and more preferably 2 to        3 provided that when the compound of Formula (1) is of Formula:        that, p, the level of sulfonation, is not in the range 1 to 2.

The value of m may represent either an integer, from when the compoundin made from a starting material already bearing the water-solubilisinggroup, or it may represent an average, from when the water-solubilisinggroup is introduced after synthesis of the compound of Formula (4) e.g.via sulfonation.

Preferably each G independently is selected from sulfo, phosphate andcarboxy, more preferably all groups represented by G are sulfo.

The preferred anthracene group is of Formula (5)

wherein

-   -   Q is a hydroxy, amino or carboxy group positioned adjacent to        the —N═N— group shown in Formula (1);    -   G is a water-solubilising group; and    -   m is greater than 1, preferably 1 to 4 more preferably 2 to 3.

The value of m may represent either an integer, from when the compoundin made from a starting material already bearing the water-solubilisinggroup, or it may represent an average, from when the water-solubilisinggroup is introduced after synthesis of the compound of Formula (5) e.g.via sulfonation.

Preferably each G independently is selected from sulfo, phosphate andcarboxy, more preferably all groups represented by G are sulfo.

The preferred optionally substituted acenaphthylene group is of Formula(6):

wherein

-   -   Q is a hydroxy, amino or carboxy group positioned adjacent to        the —N═N— group shown in Formula (1);    -   G is a water-solubilising group; and    -   m is 0 to 4, more preferably 0 to 2 and especially 1 to 2.

The value of m may represent either an integer, from when the compoundin made from a starting material already bearing the water-solubilisinggroup, or it may represent an average, from when the water-solubilisinggroup is introduced after synthesis of the compound of Formula (3) e.g.via sulfonation.

Preferably each G independently is selected from sulfo, phosphate andcarboxy, more preferably all groups represented by G are sulfo.

The heterocyclic ring containing X may have substituent(s) on theheterocyclic ring or the substituent(s) on the heterocyclic ring mayform a condensed ring through further condensation, and the condensedring so formed may also carry substituent(s).

The heterocyclic ring containing X is preferably an optionallysubstituted imidazole ring, an optionally substituted pyridine ring, anoptionally substituted pyrazole ring, an optionally substituted triazolering, an optionally substituted isoxazole ring, an optionallysubstituted thiazole ring, an optionally substituted thiadiazole ring,an optionally substituted pyridazine ring, an optionally substitutedpyrimidine ring, an optionally substituted pyrazine ring, an optionallysubstituted benzothiazole ring, an optionally substituted benzoxazolering or an optionally substituted benzimidazole ring.

It is preferred that the heterocyclic ring containing X is an optionallysubstituted imidazole ring, an optionally substituted pyrazole ring, anoptionally substituted thiazole ring, an optionally substitutedthiadiazole ring or, more preferably, an optionally substitutedthiadiazole ring, an optionally substituted triazole ring, an optionallysubstituted pyridine ring or an optionally substituted oxadiazole ring,especially a pyridine ring or a triazole ring.

When the heterocyclic ring containing X (which may form one or morecondensed rings) has one or more substituents, the substituents arepreferably each independently selected from: alkyl group which may besubstituted (e.g., alkyl group having 1 to 6 carbon atoms such as methylgroup, ethyl group, or the like, carboxymethyl group, carboxyethylgroup, trifluoromethyl group, or the like); aryl group which may besubstituted (preferably aryl group having 6 to 10 carbon atoms, e.g.,phenyl group, naphthyl group, or the like); aralkyl group which may besubstituted (benzyl group or the like, preferably aralkyl group having 7to 10 carbon atoms in total); allyl group which may be substituted(e.g., vinyl group, 2-propenyl group, or the like); alkoxy group whichmay be substituted (preferably alkoxy group having 1 to 6 carbon atoms,e.g., methoxy group, ethoxy group, or the like); aryloxy group which maybe substituted (e.g., phenoxy group, or the like); acyloxy group whichmay be substituted (preferably alkanoyloxy group having 2 to 7 carbonatoms such as acetyloxy group, benzoyloxy group, or the like);alkoxycarbonyl group which may be substituted (preferably alkoxycarbonylgroup having 2 to 7 carbon atoms, e.g., methoxycarbonyl, ethoxycarbonyl,or the like); aryloxycarbonyl group which may be substituted (e.g.,phenoxycarbonyl group, naphthyloxycarbonyl group, or the like);carbamoyl group which may be substituted; acyl group which may besubstituted (e.g., acyl group having 2 to 10 carbon atoms such as acetylgroup, or the like); carboxyl group; hydroxyl group; cyano group;acylamino group which may be substituted (e.g., alkanoylamino grouphaving 2 to 7 carbon atoms such as acetylamino group, benzoylaminogroup, or the like); nitro group; halogen atom (e.g., chlorine atom,bromine atom, fluorine atom, or the like); phosphono group; sulfo group;mercapto group; alkylthio group which may be substituted (e.g.,alkylthio group having 1 to 6 carbon atoms such as methylthio group orethylthio group, or the like); alkylsulfoxy group which may besubstituted (e.g., alkylsulfoxyl group having 1 to 6 carbon atoms suchas methylsulfoxy group or ethylsulfoxy group, or the like);alkylsulfonyl group which may be substituted (e.g., alkylsulfonyl grouphaving 1 to 6 carbon atoms such as methylsulfonyl group or ethylsulfonylgroup, or the like); or thiocyanato group.

Preferred optionally substituted imidazole rings are of Formula (7):

wherein each R¹ may be either the same or different and R¹ is selectedfrom: alkyl group which may be substituted, aryl group which may besubstituted, aralkyl group which may be substituted, alkoxy group whichmay be substituted, aryloxy group which may be substituted, acyloxygroup which may be substituted, alkoxycarbonyl group which may besubstituted, aryloxycarbonyl group which may be substituted, carboxylgroup, carbamoyl group which may be substituted, hydroxyl group, acylgroup which may be substituted, cyano group, acylamino group which maybe substituted, nitro group, halogen atom, sulfo group, mercapto group,alkylthio group which may be substituted and thiocyanato group, R¹ mayfurther form a condensed ring together with an imidazole ring; crepresents an integer of 0 to 2; and R² represents hydrogen atom, analkyl group which may be substituted, an aryl group which may besubstituted or an allyl group which may be substituted.

In particular, R¹ is preferably an alkoxycarbonyl group which may besubstituted, carboxyl or cyano.

Preferably R² is a hydrogen atom or an alkyl group which may besubstituted. Most preferrably c is 2, both of the two R¹'s are cyano orcarboxy and R² is a hydrogen atom or an alkyl group which may besubstituted.

Preferred optionally substituted pyrazole rings are of Formula (8):

wherein each R³ may be either the same or different and R³ is selectedfrom: alkyl group which may be substituted, aryl group which may besubstituted, aralkyl group which may be substituted, alkoxycarbonylgroup which may be substituted, aryloxycarbonyl group which may besubstituted, carboxyl group, carbamoyl group which may be substituted,hydroxyl group, cyano group or sulfo group; d represents an integer of 0to 2; and R⁴ represents hydrogen atom, alkyl group which may besubstituted or aryl group which may be substituted.

Preferred optionally substituted thiazole rings are of Formula (9):

wherein each R⁵ may be either the same or different and R⁵ is selectedfrom: alkyl group which may be substituted, aryl group which may besubstituted, aralkyl group which may be substituted, alkoxy group whichmay be substituted, aryloxy group which may be substituted, acyloxygroup which may be substituted, alkoxycarbonyl group which may besubstituted, aryloxycarbonyl group which may be substituted, carboxylgroup, hydroxyl group, acyl group which may be substituted, cyano group,acylamino group which may be substituted, nitro group, halogen atom,sulfo group, alkylthio group which may be substituted or arylthio groupwhich may be substituted, and R⁵ may further form a condensed ringtogether with thiazole ring; and e represents an integer of 0 to 2.

Preferably R⁵ is alkyl group which may be substituted, e=0 and R⁵ isabsent, or R⁵ forms a condensed ring together with thiazole ring.

Preferred optionally substituted thiadiazole rings are of Formula (10):

wherein R⁸ is selected from: hydrogen atom, alkyl group which may besubstituted, aryl group which may be substituted, aralkyl group whichmay be substituted, mercapto group, alkylthio group which may besubstituted, alkylsulfoxy group which may be substituted oralkylsulfonyl group which may be substituted.

R⁶ is preferably a hydrogen atom or alkyl group which may besubstituted.

Preferred optionally substituted triazole rings are of Formula (11):

wherein R⁷ represents hydrogen atom, alkyl group which may besubstituted, aryl group which may be substituted, aralkyl group whichmay be substituted, alkoxy group which may be substituted, aryloxy groupwhich may be substituted, acyloxy group which may be substituted,alkoxycarbonyl group which may be substituted, aryloxycarbonyl groupwhich may be substituted, carboxyl group, carbamoyl group, hydroxylgroup, acyl group which may be substituted, cyano group, amino groupwhich may be substituted, acylamino group which may be substituted,nitro group, halogen atom, sulfo group, mercapto group, alkylthio groupwhich may be substituted, alkylsulfoxy group which may be substituted,alkylsulfonyl group which may be substituted or thiocyanato group; R⁸represents hydrogen atom, alkyl group which may be substituted, arylgroup which may be substituted or allyl group which may be substituted;and R⁷ and R⁸ may form a condensed ring together with a triazole ring.

A preferred optionally substituted tetrazole ring is of Formula (12):

wherein R⁹ represents hydrogen atom, alkyl group which may besubstituted, aryl group which may be substituted, aralkyl group whichmay be substituted, alkoxycarbonyl group which may be substituted,aryloxycarbonyl group which may be substituted, carboxyl group,carbamoyl group, hydroxyl group, cyano group or sulfo group.

A preferred optionally substituted oxadiazole ring is of Formula (13):

wherein R¹⁰ represents hydrogen atom, alkyl group which may besubstituted, aryl group which may be substituted, aralkyl group whichmay be substituted, alkoxy group which may be substituted, aryloxy groupwhich may be substituted, acyloxy group which may be substituted,alkoxycarbonyl group which may be substituted, aryloxycarbonyl groupwhich may be substituted, carboxyl group, hydroxyl group, acyl groupwhich may be substituted, cyano group, acylamino group which may besubstituted, nitro group, halogen atom, sulfo group, alkylthio groupwhich may be substituted or arylthio group which may be substituted.

Another preferred optionally substituted oxadiazole ring is of Formula(14):

wherein R¹¹ represents hydrogen atom, alkyl group which may besubstituted, aryl group which may be substituted, aralkyl group whichmay be substituted, alkoxy group which may be substituted, aryloxy groupwhich may be substituted, acyloxy group which may be substituted,alkoxycarbonyl group which may be substituted, aryloxycarbonyl groupwhich may be substituted, carboxyl group, hydroxyl group, acyl groupwhich may be substituted, cyano group, acylamino group which may besubstituted, nitro group, halogen atom, sulfo group, alkylthio groupwhich may be substituted or arylthio group which may be substituted.

A preferred optionally substituted thiadiazole ring is of the Formula(15):

wherein R¹² represents hydrogen atom, alkyl group which may besubstituted, aryl group which may be substituted, aralkyl group whichmay be substituted, alkoxy group which may be substituted, aryloxy groupwhich may be substituted, acyloxy group which may be substituted,alkoxycarbonyl group which may be substituted, aryloxycarbonyl groupwhich may be substituted, carboxyl group, hydroxyl group, acyl groupwhich may be substituted, cyano group, acylamino group which may besubstituted, nitro group, halogen atom, sulfo group, alkylthio groupwhich may be substituted or arylthio group which may be substituted.

In the case where R⁵to R¹² in the general Formulae (7) to (15) havesubstituents, preferred examples of the substituents include alkyl oralkoxy group having not greater than 10 carbon atoms, preferably notgreater than 6 carbon atoms, particularly from not smaller than 1 to notgreater than 5 carbon atoms, carboxyl group, and cyano group. Preferredamong these substituents are alkyl group, carboxyl group, and cyanogroup. Particularly preferred among these substituents are carboxylgroup and cyano group.

The above mentioned heterocyclic rings exist in a variety of tautomericforms and all such tautomers are included as part of the presentinvention.

Particularly preferred optionally substituted triazole rings are of theFormula (16), (17), (18), (19) or (20)

wherein:

-   -   Z is H, —OH, —Br, —Cl, —F, —CN, —NO₂, —PO₃H₂, —SO₃H, —CO₂H,        optionally substituted phosphoramide, optionally substituted        alkyl, optionally substituted alkenyl, optionally substituted        alkynyl, optionally substituted aryl, optionally substituted        aralkyl, —SR¹³, —SO₂R¹³, —SO2NR¹⁴R¹⁵, —SOR¹³, —OR¹³, —C(O)R¹³,        —C(O)OR¹³, —C(O)NR¹⁴R¹⁵, —NR¹⁴R¹⁵, —NHCOR¹³; and    -   Y is CF₃ or any one of the groups defined for Z; and        wherein:    -   R¹³, R¹⁴ and R¹⁵ are each independently H, optionally        substituted alkyl, optionally substituted alkenyl, optionally        substituted alkynyl, optionally substituted aryl or optionally        substituted aralkyl; or    -   R¹⁴ and R¹⁵ together with the nitrogen to which they are        attached form an optionally substituted 5- or 6-membered ring.

When Y or Z is optionally substituted phosphoramide the phosphoramide ispreferably substituted by optionally substituted alkyl, optionallysubstituted aryl or optionally substituted aralkyl. Preferredsubstituents include for example methyl, ethyl, n-propyl, iso-propyl,hydroxyethyl, optionally substituted phenyl or optionally substitutedbenzyl.

When Y or Z is optionally substituted alkyl, the alkyl group ispreferably optionally substituted C₁₋₄-alkyl, more preferably C₁₋₄-alkyloptionally substituted by halo, hydroxy, carboxy, sulfo or cyano.Examples include methyl, ethyl, n-propyl, iso-propyl, trifluoromethyl,hydroxyethyl, cyanoethyl, sulfopropyl and carboxyethyl. However, when Yor Z is optionally substituted alkyl it is especially preferred that thealkyl group is methyl, ethyl or trifluoromethyl.

When Y or Z is optionally substituted alkenyl, Y or Z is preferablyoptionally substituted C₂-C₄ alkenyl.

When Y or Z is optionally substituted alkynyl, Y or Z is preferablyoptionally substituted C₂-C₆ alkynyl.

When Y or Z is optionally substituted aryl the aryl group is preferablyoptionally substituted phenyl, optionally substituted naphthyl oroptionally substituted heteroaryl. It is especially preferred that whenY is optionally substituted aryl it is optionally substituted phenyl oroptionally substituted heteroaryl.

Preferred optional substituents on Y when Y is optionally substitutedaryl include sulfo, carboxy, nitro, cyano, halo (preferably chloro),alkoxy (preferably C₁₋₈-alkoxy), alkyl ((preferably C₁₋₆-alkyl)optionally substituted by halogen (preferably fluoro), hydroxy, carboxy,phosphoric acid and sulfo. Especially preferred optional substituents onY when Y is optionally substituted aryl are selected from C₁₋₄-alkyl,carboxy, phosphoric acid and sulfo. However, it is most preferred thatwhen Y is optionally substituted aryl that the aryl group is substitutedby carboxy.

Preferred optional substituents on Z when Z is optionally substitutedaryl include sulfo, carboxy, nitro, cyano, halo (preferably chloro),alkoxy (preferably C₁₋₆-alkoxy), alkyl (preferably C₁₋₆-alkyl)optionally substituted by halogen (preferably fluoro), hydroxy, carboxy,phosphoric acid and sulfo. Especially preferred optional substituents onZ as optionally substituted aryl are selected from carboxy or halogen(preferably chloro).

When Y or Z is optionally substituted aralkyl the aralkyl group ispreferably optionally substituted benzyl.

However, Y in Formulae (16), (17), (18), (19) or (20) is preferably H,thiol, carboxy, halo (preferably chloro), alkyl ((preferably C₁₋₆-alkyl)optionally substituted by hydroxy, carboxy, halo (preferably fluoro) orsulfo. It is especially preferred that Y in Formulae (16) to (20) is H,C₁₋₄-alkyl or carboxy or sulfo. However, it is most especially preferredthat Y is H, CO₂H or sulfo.

Z in Formulae (16) to (20) is preferably H, ethylester or alkyl(preferably C₁₋₄-alkyl) optionally substituted by hydroxy, carboxy, halo(preferably fluoro) or sulfo. It is especially preferred that Z inFormulae (16) to (20) is H or C₁₋₄-alkyl. However, it is most especiallypreferred that Z is H.

In one embodiment Z is H and Y is H, CO₂H or sulfo.

R¹³, R¹⁴ and R¹⁵ are each independently preferably H, optionallysubstituted C₁₋₄-alkyl or optionally substituted aryl, more preferablyH, C₁₋₄-alkyl optionally substituted by hydroxy, carboxy, sulfo or cyanoor phenyl optionally substituted by hydroxy, carboxy, sulfo, nitro,trifluoromethyl or cyano. Examples of groups represented by R¹³, R¹⁴ andR¹⁵ include methyl, ethyl, n-propyl, iso-propyl, hydroxyethyl,cyanoethyl, sulfopropyl, carboxyethyl or carboxyphenyl. It is especiallypreferred however that R¹³, R¹⁴ and R¹⁵ are H, optionally substitutedC₁₋₄-alkyl for example, trifluoromethyl, hydroxyethyl or cyanoethyl, oroptionally substituted aryl for example phenyl optionally substituted bycarboxy; or R¹⁴ and R¹⁵ together with the nitrogen to which they areattached form a 5- or 6-membered ring (preferably morpholine, piperidineor piperazine).

A preferred optionally substituted pyridine ring is of Formula (21):

wherein each R¹⁶ may be either the same or different and R¹⁶ is asdescribed and preferred for Y in Formula (16) to (20) above; frepresents an integer of 0 to 4.

Preferably f is 0.

A preferred optionally substituted pyrimidine ring is of Formula (22):

wherein each R¹⁷ may be either the same or different and R¹⁷ is asdescribed and preferred for Y in Formula (16) to (20) above; grepresents an integer of 0 to 3.

A preferred optionally substituted pyrazine ring is of Formula (23):

wherein each R¹⁸ may be either the same or different and R¹⁸ is asdescribed and preferred for Y in Formula (16) to (20) above; hrepresents an integer of 0 to 3.

It is particularly preferred that the 5- to 7-membered heterocyclic ringis an optionally substituted pyridine, especially a moiety of Formula(21), or a 1,2,4-triazole especially a moiety of Formulae (18) to (20).

The transition metal salt preferably comprises one or more of thefollowing metals: nickel, chromium, cobalt, copper, zinc, iron ormanganese.

It is particularly preferred that the transition metal salt comprisesnickel or copper, especially nickel.

The compound of Formula (1) is preferably chelated to the transitionmetal in the ratio 1:1, 2:1, 2:2 or 2:3 respectively, especially in theratio 1:1 or 2:1 respectively.

When there is more than one ligand of Formula (1) present in the metalchelate compound then the ligands of Formula (1) may be the same ordifferent but preferably they are the same.

The metal chelate compound obtainable from a compound of Formula (1) mayalso comprise 1 or more additional ligands. These ligands may becoloured or colourless and when there is more than 1 they may be thesame or different.

Compounds of Formula (1) and the metal chelate compounds obtainable froma compound of Formula (1), as described herein, may exist in tautomericforms other than those shown in this specification. These tautomers arealso included within the scope of the present inventions.

The metal chelate compounds obtainable from compounds of Formula (1) mayalso exist in different geometries e.g. octahedral or square planar.These different geometric forms are also included in the scope of thepresent invention.

It is especially preferred that the metal chelate compounds obtainablefrom compounds of Formula (1) are magenta in colour. Preferably themetal chelate compounds obtainable from compounds of Formula (1) have achroma of at least 50 when printed on plain paper. Preferably the metalchelate compounds obtainable from compounds of Formula (1) arewater-soluble, more preferably they have a solubility in water at 20° C.of 0.5 to 15, more preferably 0.6 to 10% by weight.

The metal chelate compounds obtainable from compounds of Formula (1) ofthe first aspect of the present invention provide prints which exhibit ahigh light-fastness, ozone fastness, wet fastness and good opticaldensity.

Compounds of Formula (1) are preferably free from fibre reactive groups.The term fibre reactive group is well known in the art and is describedfor example in EP 0356014 A1. Fibre reactive groups are capable, undersuitable conditions, of reacting with the hydroxyl groups present incellulosic fibres or with the amino groups present in natural fibres toform a covalent linkage between the fibre and the dye. As examples offibre reactive groups preferably not present in the compounds of thefirst aspect of the present invention there may be mentioned aliphaticsulfonyl groups which contain a sulphate ester group in thebeta-position to the sulphur atom, e.g. beta-sulphatoethylsulfonylgroups, alpha, beta-unsaturated acyl radicals of aliphatic carboxylicacids, for example acrylic acid, alpha-chloro-acrylic acid,alpha-bromoacrylic acid, propiolic acid, maleic acid and mono- anddichloro maleic; also the acyl radicals of acids which contain asubstituent which reacts with cellulose in the presence of an alkali,e.g. the radical of a halogenated aliphatic acid such as chloroaceticacid, beta-chloro and beta-bromopropionic acids and alpha,beta-dichloro- and dibromopropionic acids or radicals of vinylsulfonyl-or beta-chloroethylsulfonyl- orbeta-sulphatoethyl-sulfonyl-endo-methylene cyclohexane carboxylic acids.Other examples of cellulose reactive groups are tetrafluorocyclobutylcarbonyl, trifluoro-cyclobutenyl carbonyl, tetrafluorocyclobutylethenylcarbonyl, trifluoro-cyclobutenylethenyl carbonyl; activated halogenated1,3-dicyanobenzene radicals; and heterocyclic radicals which contain 1,2 or 3 nitrogen atoms in the heterocyclic ring and at least onecellulose reactive substituent on a carbon atom of the ring.

The compounds of Formula (1) and the metal chelate compound obtainablefrom compounds of Formula (1) may be in the free acid or salt form.Preferred salts are water-soluble, for example alkali metal salts,especially lithium, sodium, potassium, ammonium, substituted ammoniumand mixed salts thereof. Preferred alkali metal salts are those withsodium or lithium ammonium and substituted alkyl ammonium salts.

Preferred ammonium and substituted ammonium salts have cations of theformula ⁺NV₄ wherein each V independently is H or optionally substitutedalkyl, or two groups represented by V are H or optionally substitutedalkyl and the remaining two groups represented by V, together with the Natom to which they are attached, form a 5- or 6-membered ring(preferably a morpholinyl, pyridinyl or piperidinyl ring).

Preferably each V independently is H or C₁₋₄-alkyl, more preferably H,CH₃ or CH₃CH₂, especially H.

Examples of cations include ⁺NH₄, morpholinium, piperidinium,pyridinium, (CH₃)₃N⁺H, (CH₃)₂N⁺H₂, H₂N⁺(CH₃)(CH₂CH₃), CH₃N⁺H₃,CH₃CH₂N⁺H₃, H₂N⁺(CH₂CH₃)₂, CH₃CH₂CH₂N⁺H₃, (CH₃)₂CHN⁺H₃, N⁺(CH₃)₄,N⁺(CH₂CH₃)₄, N-methyl pyridinium, N,N-dimethyl piperidinium andN,N-dimethyl morpholinium.

Sodium, lithium, potassium, ammonium, or substituted ammonium salts arepreferred because we have found that these salts provide prints whichexhibit a high light-fastness when incorporated into an ink-jet printingink.

The metal chelate compounds may be prepared using techniques that arewell known in the art. For example a suitable method comprises mixing asolution of a transition metal salt and a solution of a compound ofFormula (1), preferably in aqueous solution.

Normally 0.5 to 24 hours is sufficient for the transition metal salt toform a metal chelate compound with the compound of Formula (1).

The compounds of Formula (1) may be prepared by, for example,diazotising a compound of the formula Ar—NH₂ to give a diazonium saltand coupling the resultant diazonium salt with the desired hydroxylatedcoupler. A protection/deprotection sequence employing, preferably, theN-oxide derivatives may be required. Methods for introducing andremoving the protecting group(s) are well known in the art.

The diazotisation is preferably performed at a temperature below 6° C.,more preferably at a temperature in the range −10° C. to 5° C.Preferably the diazotisation is performed in water, preferably at a pHbelow 7. Dilute mineral acid, e.g. HCl or H₂SO₄, are often used toachieve the desired acidic conditions.

An alternative preparation of such compounds involves the condensationof a hydrazine derivative with a diketone, to give rise to a hydrazone.If desired, sulfonation of the hydrazone can be achieved under standardconditions using fuming sulphuric acid.

The product of the above process may be converted to a salt byconventional techniques as hereinbefore described. Alternatively theproduct may be isolated in its free acid form by acidifying the reactionmixture, preferably using a mineral acid, for example hydrochloric acidand when the product precipitates as a solid it may be separated fromthe mixture by filtration. Unwanted anions may be and preferably areremoved from the product of the process by dialysis, osmosis,ultrafiltration or a combination thereof. Alternatively, the productsolution is subjected to the above purification directly withoutisolation of the product.

The present invention also covers mixtures comprising two or moredifferent metal chelate compounds of the present invention or saltsthereof. Furthermore, the compounds of the first aspect of the presentinvention may be mixed with other dyes, especially those listed in theInternational Colour Index, to adjust the shade or other properties asdesired.

According to a second aspect of the present invention there is provideda composition comprising (a) one or more metal chelate compound(s)according to the first aspect of the present invention; and (b) a liquidmedium.

The liquid medium preferably comprises:

(i) water;

(ii) a mixture of water and an organic solvent; or

(iii) an organic solvent free from water.

The number of parts by weight of component (a) of the ink is preferablyfrom 0.01 to 30, more preferably 0.1 to 20, especially from 0.5 to 15,and more especially from 1 to 5 parts. The number of parts by weight ofcomponent (b) is preferably from 99.99 to 70, more preferably from 99.9to 80, especially from 99.5 to 85, and more especially from 99 to 95parts. The number of parts (a)+(b) and all parts mentioned herein are100 by weight.

Preferably component (a) is completely dissolved in component (b).Preferably component (a) has a solubility in component (b) at 20° C. ofat least 10%. This allows the preparation of concentrates which may beused to prepare more dilute inks and reduces the chance of thecompound(s) of component (a) of the ink precipitating if evaporation ofthe liquid medium occurs during storage.

When the liquid medium comprises a mixture of water and an organicsolvent, the weight ratio of water to organic solvent is preferably from99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from95:5 to 80:20.

It is preferred that the organic solvent present in the mixture of waterand organic solvent is a water-miscible organic solvent or a mixture ofsuch solvents. Preferred water-miscible organic solvents includeC₁₋₆-alkanols, preferably methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol andcyclohexanol; linear amides, preferably dimethylformamide ordimethylacetamide; ketones and ketone-alcohols, preferably acetone,methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscibleethers, preferably tetrahydrofuran and dioxane; diols, preferably diolshaving from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethyleneglycol, propylene glycol, butylene glycol, pentylene glycol, hexyleneglycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferablydiethylene glycol, triethylene glycol, polyethylene glycol andpolypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol;mono-C₁₋₄-alkyl ethers of diols, preferably mono-C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially 2-methoxyethanol,2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol,2-[2-(2-methoxyethoxy)ethoxy]ethanol,2-[2-(2-ethoxyethoxy)ethoxy]-ethanol and ethyleneglycol monoallylether;cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone,N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclicesters, preferably caprolactone; sulfoxides, preferably dimethylsulfoxide and sulfolane. Preferably the liquid medium comprises waterand 2 or more, especially from 2 to 8, water-miscible organic solvents.

Especially preferred water-soluble organic solvents are cyclic amides,especially 2-pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone;diols, especially 1,5-pentane diol, ethyleneglycol, thiodiglycol,diethyleneglycol and triethyleneglycol; and mono-C₁₋₄-alkyl andC₁₋₄-alkyl ethers of diols, more preferably mono-C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially2-methoxy-2-ethoxy-2-ethoxyethanol.

Examples of further suitable ink media comprising a mixture of water andone or more organic solvents are described in U.S. Pat. No. 4,963,189,U.S. Pat. No. 4,703,113, U.S. Pat. No. 4,626,284 and EP 4,251,50A.

When the liquid medium comprises an organic solvent free from water,(i.e. less than 1% water by weight) the solvent preferably has a boilingpoint of from 30° to 200° C. The organic solvent may bewater-immiscible, water-miscible or a mixture of such solvents.Preferred water-miscible organic solvents are any of thehereinbefore-described water-miscible organic solvents and mixturesthereof. Preferred water-immiscible solvents include, for example,aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinatedhydrocarbons, preferably CH₂Cl₂; and ethers, preferably diethyl ether;and mixtures thereof.

When the liquid medium comprises a water-immiscible organic solvent,preferably a polar solvent is included because this enhances solubilityof the dye in the liquid medium. Examples of polar solvents includeC₁₋₄-alcohols. In view of the foregoing preferences it is especiallypreferred that where the liquid medium is an organic solvent free fromwater it comprises a ketone (especially methyl ethyl ketone) and/or analcohol (especially a C₁₋₄-alkanol, such as ethanol or propanol).

The organic solvent free from water may be a single organic solvent or amixture of two or more organic solvents. It is preferred that when themedium is an organic solvent free from water it is a mixture of 2 to 5different organic solvents: This allows a medium to be selected whichgives good control over the drying characteristics and storage stabilityof the ink.

Ink media comprising an organic solvent free from water are particularlyuseful where fast drying times are required and particularly whenprinting onto hydrophobic and non-absorbent substrates, for exampleplastics, metal and glass.

An especially preferred ink comprises:

-   (a) from 1 to 10 parts in total of a metal chelate compound of    Formula (1) as hereinbefore defined;-   (b) from 2 to 60, more preferably 5 to 40 parts of water-miscible    organic solvent; and-   (c) from 30 to 97, more preferably 40 to 85 parts of water;    wherein all parts are by weight.

Preferably the sum of the parts (a)+(b)+(c)=100.

When the liquid medium in the ink comprises a mixture of water and anorganic solvent; or an organic solvent free from water, component (a) ofthe ink may comprise a compound as hereinbefore defined in relation tothe first aspect of the invention.

Preferred low melting solid media have a melting point in the range from60° C. to 125° C. Suitable low melting point solids include long chainfatty acids or alcohols, preferably those with C₁₈₋₂₄ chains, andsulfonamides. The compound of the first aspect of the present inventionmay be dissolved in the low melting point solid or may be finelydispersed in it.

Preferably the composition according to the second aspect of theinvention is an ink suitable for use in an ink-jet printer.

The inks according to the present invention may also contain additionalcomponents conventionally used in ink-jet printing inks, for exampleviscosity and surface tension modifiers, corrosion inhibitors, biocides,kogation reducing additives, anti-cockle agents to reduce paper curlingand surfactants which may be ionic or non-ionic.

The pH of the ink is preferably from 4 to 11, more preferably from 7 to10.

The viscosity of the ink at 25° C. is preferably less than 50 cP, morepreferably less than 20 cP and especially less than 5 cP.

When the inks according to the invention are used as ink-jet printinginks, the ink preferably has a concentration of less than 500 parts permillion, more preferably less than 100 parts per million of halide ions.

It is also preferred that the ink has less than 100, more preferablyless than 50 parts per million of divalent and trivalent metals (otherthan any divalent and trivalent metal ions bound to a compound ofFormula (1) or any other component of the ink), wherein parts refer toparts by weight relative to the total weight of the ink.

Preferably an ink suitable for use in an ink-jet printer has beenfiltered through a filter having a mean pore size below 10 μm, morepreferably below 3 μm, especially below 2 μm, more especially below 1μm. This filtration removes particulate matter that could otherwiseblock the fine nozzles found in many ink-jet printers.

A third aspect of the present invention provides a process for printingan image on a substrate comprising applying thereto by means of anink-jet printer an ink according to the second aspect of the invention.

The ink used in this process is preferably as defined in the secondaspect of the present invention.

The ink-jet printer preferably applies the ink to the substrate in theform of droplets which are ejected through a small orifice onto thesubstrate. Preferred ink-jet printers are piezoelectric ink-jet printersand thermal ink-jet printers. In thermal ink-jet printers, programmedpulses of heat are applied to the ink in a reservoir by means of aresistor adjacent to the orifice, thereby causing the ink to be ejectedin the form of small droplets directed towards the substrate duringrelative movement between the substrate and the orifice. Inpiezoelectric ink-jet printers the oscillation of a small crystal causesejection of the ink from the orifice. Alternately the ink can be ejectedby an electromechanical actuator connected to a moveable paddle orplunger, for example as described in International Patent Application WO00/48938 and International Patent Application WO 00/55089.

The substrate is preferably paper, plastic, a textile, metal or glass,more preferably paper, an overhead projector slide or a textilematerial, especially paper. Preferred papers are plain or treated paperswhich may have an acid, alkaline or neutral character. Glossy papers areespecially preferred. More especially photographic quality paper ispreferred

Examples of commercially available papers include, HP Premium CoatedPaper, HP Photopaper (all available from Hewlett Packard Inc.), StylusPro 720 dpi Coated Paper, Epson Photo Quality Glossy Film, Epson PhotoQuality Glossy Paper (available from Seiko Epson Corp.), Canon HR 101High Resolution Paper, Canon GP 201 Glossy Paper, Canon HG 101 HighGloss Film (all available from Canon Inc.), Wiggins Conqueror paper(available from Wiggins Teape Ltd), Xerox Acid Paper and Xerox Alkalinepaper (available from Xerox).

A fourth aspect of the present invention provides a substrate,preferably a paper, an overhead projector slide or a textile material,printed with a metal chelate compound according to the first aspect ofthe invention, printed with an ink according to the second aspect of theinvention or printed by means of a process according to the third aspectof the present invention.

According to a fifth aspect of the present invention there is providedan ink-jet printer cartridge comprising a chamber and ink, wherein theink is present in the chamber and the ink is as described in the secondaspect of the present invention.

According to a sixth aspect of the present invention there is providedan ink-jet printer containing an ink-jet printer cartridge, wherein theink-jet printer cartridge is as defined in the sixth aspect of thepresent invention.

The invention is further illustrated by the following Examples in whichall parts and percentages are by weight unless otherwise stated.

EXAMPLE 1

Preparation of a Nickel Chelate of a Compound of Formula:

Stage 1 (a)

Phenanthrenequinone (2.08 g, 0.01 mol) and 2-hydrazinopyridine (1.09 g,0.01 mol) were added to stirred glacial acetic acid (25 ml). The mixturewas heated to 100° C. for two hours and then allowed to cool to roomtemperature and filtered. The filtrate was evaporated under reducedpressure to leave a tarry material. This residue was ground under water,allowing the resultant solid to be collected by filtration. The productwas washed with water and then dried in an oven at 50° C. to give anorange/red solid.

Stage 1(b)

The azophenanthrene prepared in stage 1(a) (2.99 g, 0.01 mol) was addedto an ice-cold stirred solution of 10% fuming sulphuric acid (35 ml).The reaction mixture was heated to 100° C. and stirred for a further 2hours. The reaction mixture was poured carefully onto ice beforeincreasing the pH to pH8 using concentrated sodium hydroxide,maintaining the temperature with an ice/water bath. The mixture wasdialysed to low conductivity, filtered and the sulfonated ligandisolated by evaporating under reduced pressure. The product was shown tobe a mixture of di- and tri-sulfonated material, by reverse phase HPLCusing a octadecasilyl column and a gradient elution from 0.01 M ammoniumacetate solution to a final solution of 90% acetonitrile:10% ammoniumacetate. The majority of the product is believed to be the title productthough some product in which the pyridine ring was sulfonated may alsobe present. The relative amounts of the di- and tri-sulfonated specieswas estimated from the peaks corresponding to each species.

Stage 1(c)

A solution of nickel acetate tetrahydrate (1.25 g, 0.005 mol) in water(15 ml) was added dropwise to the product from stage (b) (4.59 g, 0.01mol) dissolved in water (250 ml) at pH7. The reaction mixture wasstirred at room temperature and the pH of the solution raised to pH8with 2MNaOH before being dialysed to low conductivity. The titlecompound was obtained by filtering the solution and then evaporating thefiltrate under reduced pressure.

EXAMPLE 2

Preparation of a Nickel Chelate of a Compound of Formula:

The nickel chelate of this compound was prepared using an analogousprocess to that in Example 1 except that in stage (b) 20% fumingsulphuric acid was used in place of 10% fuming sulphuric acid. As inExample 1the product as produced may also contain some material wherethe pyridine ring is sulfonated.

EXAMPLES 3 to 7

The compounds described in Table 1 were prepared using an analogousprocess to that described in Example 1 except that in stage 1(a) analternative hydrazine was used in place of 2-hydrazinopyridine andinstead of the screened reaction mixture being isolated by evaporatedunder reduced pressure as in stage 1(b), the product formed as aprecipitate which was collected by filtration. The product was thenwashed with glacial acetic acid and dried in a vacuum oven at 50° C. togive an orange/red solid. TABLE 1 Example Alternative Hydrazine Nickelchelate of compound 3

4

5

6

7

EXAMPLES 8 -11

The compounds described in Table 2 were prepared using an analogousprocess to that described in Example 1 except that in stage 1(a) analternative diketone was used in place of phenanthrenedione and thereaction was performed in denatured ethanol (100 ml) and concentratedhydrochloric acid (0.5 ml). TABLE 2 Example Alternative Diketone Nickelchelate of compound 8

9

10

11

EXAMPLES 12

Preparation of the Copper Chelate of the Compound Prepared in Example 1

This was made as described in Example 1 except that a solution of copper(II) acetate hydrate was used in place of nickel acetate tetrahydrate.

EXAMPLE 13

Preparation of the Copper Chelate of the Compound Prepared in Example 8

This was made as described in Example 8 except that a solution of copper(II) acetate hydrate was used in place of nickel acetate tetrahydrate.

EXAMPLE 14

Preparation of the Copper Chelate of the Compound Prepared in Example 9

This was made as described in Example 9 except that a solution of copper(II) acetate hydrate was used in place of nickel acetate tetrahydrate.

EXAMPLE 15

Preparation of the Copper Chelate of the Compound Prepared in Example 10

This was made as described in Example 10 except that a solution ofcopper (II) acetate hydrate was used in place of nickel acetatetetrahydrate.

EXAMPLE 16

Preparation of the Copper Chelate of the Compound Prepared in Example 11

This was made as described in Example I except that a solution of copper(II) acetate hydrate was used in place of nickel acetate tetrahydrate.

EXAMPLE 17

Preparation of a Nickel Chelate of a Compound of formula:

Stage 17(a):

3-Amino-1,2,4-triazole-5-carboxylic acid hydrate (1.28 g, 0.01 mol) wasdissolved in water (50 ml). Sodium nitrite (0.76 g, 0.011 mol) was addedand the solution was stirred until the sodium nitrite had dissolved. Themixture was then added dropwise to a cooled mix of ice-water (30 g) andconcentrated hydrochloric acid (3.0 ml) at 0-5° C. The mixture wasstirred for 30 minutes at 0-5° C. and then excess nitrous acid wasdestroyed by the addition of sulfamic acid. The resultant diazonium saltsuspension was added slowly to a solution of 6-hydroxyquinoline (1.45 g,0.01 mol) in water (100 ml) at pH 8-9 (adjusted with 2M NaOH) and cooledto below 5° C. The reaction mixture was then stirred at 0-5° C. for onehour and the product was precipitated by acidification to pH 4 with 2MHCl and collected by filtration. The product was washed with water andthen dried in a vacuum desiccator to give an orange solid.

Stage 17(b):

A solution of nickel acetate tetrahydrate (1.43 g, 0.0057 mol) in water(10 ml) was added dropwise to the product from stage 17(a) (2.5 g,0.0076 mol) dissolved in water (100 ml) at pH 7. The reaction mixturewas stirred for 2 hours at room temperature and then dialysed to lowconductivity. The title compound is obtained by evaporation underreduced pressure to afford a dark crystalline solid.

EXAMPLES 18 TO 20

The compounds described in Table 3 may be prepared using an analogousprocess to that described in Example 17 except that in stage 17(a) thecoupler shown in Table 4 is used in place of 6-hydroxyquinoline and anadditional step is employed to increase aqueous solubility.

Additional Step

The non-metallised dye prepared in step (a) (0.01 mol) is added to anice cold stirred solution of 20% fuming sulphuric acid (10 ml). Thereaction mixture is allowed to rise to room temperature and stirred fora further 1 hour. The reaction mixture is poured carefully onto ice andthe resultant solid collected by filtration. The metallisation step iscarried out as in Example 12 stage (b). TABLE 3 Example Coupler CompoundName 18

Nickel chelate of [2-hydroxysulfonated-anthracen-1-ylazo]-2H-[1,2,4]triazole-3- carboxylic acid]. (The coupleris made following the route described in Liebigs Annalen 212, 1882, 63)19

Nickel chelate of [3-hydroxy sulfonatedphenanthren-4-ylazo)-2H-[1,2,4]triazole-3- carboxylic acid]. 20

Nickel chelate of [2-hydroxy sulfonatedphenanthren-1-ylazo)-2H-[1,2,4]triazole-3- carboxylic acid].Comparative Dye 1

Comparative Dye 1 was prepared as described in Example 4 of EP1270676Aand is of Formula:

Comparative Dye 2

Comparative Dye 2 was prepared as described for Example IV of EP0902064Band is of Formula:

EXAMPLE 21 Inks and Ink-Jet Printing

The dyes described in Examples 1, 2 and 3 and Comparative Dyes 1 and 2were each converted into the corresponding inks by dissolving 3.5 partsof each in 96.5 parts of a liquid medium comprising:

-   5 parts 2-pyrrolidone;-   5 parts thiodiglycol;-   2 parts Surfynol™ 465 (a non-ionic surfactant available from Air    Products Inc.);-   88 parts water: and adjusted to pH 9.5 with ammonium hydroxide.

The inks so prepared were designated as Ink 1, Ink 2, Ink 3, ComparativeInk 1 and Comparative Ink 2 depending on which dye was incorporatedtherein

Ink-Jet Printing

Inks 1, 2 and 3 and the Comparative Inks 1 and 2 were filtered through a0.45 micron nylon filters and then incorporated into empty ink-jet printcartridges using a syringe.

The inks were then printed using an HP560C printer onto bothHewlett-Packard Premium Plus Photo Paper and Canon Professional PhotoPaper PR101 at 100% and 70% strength.

These prints were tested for ozone fastness by exposure to 1 ppm ozoneat 40° C., 50% relative humidity for 24 hrs in a Hampden 903 Ozonecabinet. The prints were also tested for light fastness by exposure to aXenon Arc lamp for 100 hours in an Atlas CI5000 Weatherometer. Fastnessof the printed ink to ozone and light was judged by the difference inthe reflected optical density (ROD) before and after exposure.

Colour measurements of the prints before and after exposure to ozone andlight were performed using a Gretag spectrolino spectrophotometer set tothe following parameters: Measuring Geometry 0°/45° Spectral Range400-700 nm Spectral Interval 20 nm Illuminant D65 Observer 2° (UE1931)Density ANSI A External Filler None

Ozone and light fastness were assessed by the change in the shade of theprint as judged via percentage ROD loss of the print, where a lowerfigure indicates higher fastness. The figures in brackets correspond tothe prints at 70% strength. TABLE 4 % ROD loss Lightfastness % ROD lossOzonefastness Canon HP Premium Canon HP Premium PR101 Plus PR101 PlusInk 1 29 (38) 21 (9)  9 (19) Not tested Ink 2 27 (38) 21 (13) 4 (12) Nottested Ink 3 25 (38) 22 (14) 1 (16) Not tested Comparative 34 (39) 24(17) 57 (61)  Not tested Ink 1 Comparative 37 (45) 33 (21) 35 (34)  Nottested Ink 2

Table 4 shows that inkjet prints prepared from compounds and inks of thepresent invention have improved light fastness and greatly improvedozone fastness when compared to prints obtained from the comparativedyes and inks.

Further Inks

The inks described in Tables A and B may be prepared wherein theCompound described in the first column is the Compound made in the aboveexample of the same number. Numbers quoted in the second column onwardsrefer to the number of parts of the relevant ingredient and all partsare by weight. The inks may be applied to paper by thermal or piezoink-jet printing.

The following abbreviations are used in Tables A and B:

PG=propylene glycol

DEG=diethylene glycol

NMP=N-methyl pyrollidone

DMK=dimethylketone

IPA=isopropanol

MEOH=methanol

2P=2-pyrollidone

MIBK=methylisobutyl ketone

P12=propane-1,2-diol

BDL=butane-2,3-diol

CET=cetyl ammonium bromide

PHO=Na₂HPO₄ and

TBT=tertiary butanol

TDG=thiodiglycol TABLE A Dye Na Example Content Water PG DEG NMP DMKNaOH Stearate IPA MEOH 2P MIBK 1 2.0 80 5 6 4 5 2 3.0 90 5 5 0.2 3 10.085 3 3 3 5 1 4 2.1 91 8 1 5 3.1 86 5 0.2 4 5 6 1.1 81 9 0.5 0.5 9 7 2.560 4 15 3 3 6 10 5 4 8 5 65 20 10 9 2.4 75 5 4 5 6 5 10 4.1 80 3 5 2 100.3 11 3.2 65 5 4 6 5 4 6 5 12 5.1 96 4 13 10.8 90 5 5 14 10.0 80 2 6 25 1 4 15 1.8 80 5 15 16 2.6 84 11 5 17 3.3 80 2 10 2 6 18 12.0 90 7 0.33 19 5.4 69 2 20 2 1 3 3 1 6.0 91 4 5

TABLE B Dye Example Content Water PG DEG NMP CET TBT TDG BDL PHO 2P PI21 3.0 80 15 0.2 5 2 9.0 90 5 1.2 5 3 1.5 85 5 5 0.15 5.0 0.2 4 2.5 90 64 0.12 5 3.1 82 4 8 0.3 6 6 0.9 85 10 5 0.2 7 8.0 90 5 5 0.3 8 4.0 70 104 1 4 11 9 2.2 75 4 10 3 2 6 10 10.0 91 6 3 11 9.0 76 9 7 3.0 0.95 5 125.0 78 5 11 6 13 5.4 86 7 7 14 2.1 70 5 5 5 0.1 0.2 0.1 5 0.1 5 15 2.090 10 16 2 88 10 17 5 78 5 12 5 18 8 70 2 8 15 5 19 10 80 8 12 1 10 8010

1. A metal chelate compound obtainable from contacting a transitionmetal salt with a compound of the Formula (1):

wherein: x represents plural atoms required to form at least oneoptionally substituted 5- to 7-membered heterocyclic ring; and Ar is anoptionally substituted stilbene, acenaphthylene, phenanthrene oranthracene group carrying a hydroxy, amino or carboxy group adjacent tothe —N═N— group shown in Formula (1) or 6-hydroxyquinoline where thehydroxy group is adjacent to the —N═N— group shown in Formula (1);provided that when the compound of Formula (1) is of Formula:

that, p, the level of sulfonation, is not in the range 1 to
 2. 2. Ametal chelate compound according to claim 1 wherein Ar is an optionallysubstituted stilbene group of the Formula (2a) or Formula (2b):

wherein Q is a hydroxy, amino or carboxy group positioned adjacent tothe —N═N— group shown in Formula (1); G is a water-solubilising group;and m and n are each independently 0 to
 2. 3. A metal chelate compoundaccording to claim 1 wherein Ar is an optionally substituted 6hydroxyquinoline group of Formula (3):

wherein: the hydroxy group is positioned adjacent to the —N═N— groupshown in Formula (1); G is a water-solubilising group; and m is 0 to 2.4. A metal chelate compound according to claim 1 wherein Ar is anoptionally substituted phenanthrene group of Formula (4a):

wherein Q is a hydroxy, amino or carboxy group positioned adjacent tothe —N═N— group shown in Formula (1); G is a water-solubilising group;and m is 2 to
 3. 5. A metal chelate compound according to claim 1wherein Ar is an optionally substituted anthracene group of Formula (5)

wherein Q is a hydroxy, amino or carboxy group positioned adjacent tothe —N═N— group shown in Formula (1); G is a water-solubilising group;and m is 1 to
 4. 6. A metal chelate compound according to claim 1wherein Ar is an optionally substituted acenaphthylene group is ofFormula (6):

wherein Q is a hydroxy, amino or carboxy group positioned adjacent tothe —N═N— group shown in Formula (1); G is a water-solubilising group;and m is 1 to
 2. 7. A metal chelate compound according to claim 2wherein G is sulfo.
 8. A metal chelate compound according to claim 1wherein the heterocyclic ring containing X is an optionally substitutedpyridine or optionally substituted triazole ring.
 9. A metal chelatecompound according to claim 1 wherein the transition metal salttransition metal salt comprises nickel or copper.
 10. A metal chelatecompound according to claim 1 wherein the transition metal salttransition metal salt comprises nickel.
 11. A composition comprising (a)one or more metal chelate compound(s) according claim 1; and (b) aliquid medium.
 12. A composition according to claim 11 which is an inksuitable for use in an ink-jet printer.
 13. An ink according to eitherclaim 11 or claim 12 which comprises: (a) from 1 to 10 parts in total ofa metal chelate compound as described in any one of claims 1 to 10; (b)from 2 to 60 parts of water-miscible organic solvent; and (c) from 30 to97 parts of water; wherein all parts are by weight.
 14. A process forprinting an image on a substrate comprising applying thereto by means ofan ink-jet printer an ink as described in claim
 1. 15. A substrateprinted with a metal chelate compound according to claim
 1. 16. Anink-jet printer cartridge comprising a chamber and ink, wherein the inkis present in the chamber and the ink is as described in either claim 12or claim
 13. 17. A substrate printed with a composition according toclaim
 11. 18. A substrate printed by a process according to claim 14.